c. 265–325
Licinius was raised to the rank of Augustus in 308 during the political reorganisation of the Tetrarchy. He established himself in the eastern empire and in 313 married Constantia, Constantine’s half-sister. The two emperors cooperated for a time, but rivalry repeatedly produced civil war and territorial settlements that increasingly favoured Constantine.
The final struggle came in 324. Constantine defeated Licinius at Adrianople and Chrysopolis, while Crispus broke his naval strength in the Hellespont. Licinius surrendered and was initially spared through Constantia’s intervention, but he was executed at Thessalonica in 325, leaving Constantine as sole ruler of the Roman Empire.
Ian Ross’s Imperial Vengeance makes Licinius the political and military rival whose continued rule in the East prevents Constantine from becoming sole emperor. Aurelius Castus is drawn into the final civil war between the two regimes, where victories on land and sea destroy Licinius’s position and reunify imperial authority under Constantine. Although the fictional protagonist carries the action, Licinius’s resistance supplies the historical conflict that drives the first half of the novel and sets up the darker dynastic crisis that follows victory.
